1. Field of the Invention
The present invention relates generally to a seat belt arrangement for an automobile vehicle, and more particularly to the seat belt locking device used with a seat belt arrangement, in which a slidable but unrotatable wedge-shaped seat belt locking member having a rotatable roller and a pair of fixed flat-sided shaft member are provided for securely locking the seat belt between adjacent flat portions of these elements in an emergency.
2. Description of the Prior Art
The background of the present invention will be explained with respect to its application to the seat belt locking device used with a seat belt arrangement for an automobile vehicle.
As is well-known, there have been various safety-belt arrangements used for an automobile vehicle so as to protect a driver or passengers seated within the passenger compartment from danger caused by a shock when the vehicle is suddenly decelerated in such an emergency case as collision. Normally, the seat belt can be spooled out easily from a retractor by the driver or passenger and is pulled toward the retractor so that the seat belt may be brought into contact with the body of the driver under an appropriate tension. In the case where an automatic locking retractor is provided for the seat belt arrangement, the seat belt is locked or stopped from being further spooled out from the retractor in case an extraordinary shock is given to the arrangement. This is because an inertia sensitive sensor can detect the shock and lock the seat belt so that the seat belt can be prevented from being further spooled out from the retractor. However, it is usually difficult to stop the seat belt immediately after the inertia sensitive sensor detects a shock, because of so-called film spool effect. The film spool effect means here that the seat belt is further spooled out from the retractor because the belt is further wound more tightly around the spool after the sensor locks the seat belt. If the belt is further spooled out from the retractor because of the film spool effect in an emergency, such as a collision, the driver or passenger may suffer damage such as colliding with the steering wheel. In order to prevent this film spool effect, it is desirable to provide a seat belt locking device, in addition to an emergency locking retractor comprising a pawl and ratchet mechanism, for improvement in the reliability and responsiveness of the locking function of the seat belt arrangement.
Various seat belt locking devices have been used for this purpose. In these cases, three rollers or the like have conventionally been provided to lock the seat belt arranged to pass around the rollers. However, since the seat belt is caught by the rollers in a straight line, various problems have been encountered as follows:
(1) The seat belt is susceptible to damage. PA1 (2) The seat belt locking force is not enough. PA1 (3) The rollers are susceptible to breakage. PA1 (4) The manufacturing and assembling of the parts is time consuming, and therefore costly.
Therefore, there has been a need for a seat belt locking device which can securely lock the belt without damaging the seat belt and also without increasing the cost of the device.
The prior-art seat belt locking devices will be described in detail after under DETAILED DESCRIPTION OF THE PRIOR ART.